Tool bit for vibration attenuation

ABSTRACT

The vibrational characteristics of a percussion tool bit are varied by affixing a restraining collar thereto in accordance with the level of dampening desired. This collar is permanently affixed to the tool bit by incorporating a rigid interlock therebetween and a special compressible material is utilized therein to withstand high operating temperatures. Where the tool bit includes a detachable work tip, the tip is configured to serve as a protective shield for the collar upon penetration into materials. As part of this configuration, a conical surface is provided to facilitate withdrawal of the tool bit from penetrated materials and to avoid inadvertent removal of the tip during penetration.

United States Patent [191 Swisher 1 1 3,848,931 51 Nov. 19, 1974 TOOL BIT FOR VIBRATION ATTENUATION [75] Inventor: James A. Swisher, Easton, Conn.

[58] Field of Search... 299/37, 94; 173/139, DIG. 2; 175/56, 325, 408; 181/33 K, 33 L, 36 A; 279/l9l9.7; 308/4 A [56] References Cited UNITED STATES PATENTS 2,043,442 6/1936 McNeil 279/19 X 2,997,024 8/1961 McLean 173/139 3,655,244 4/1972 Swisher 299/94 3,662,855 5/1972 Adams et a1 173/139 X FOREIGN PATENTS OR APPLICATIONS 22,436 9/1929 Australia H 175/325 Primary Examiner-Ernest R. Purser Attorney, Agent, or FirmWooster, Davis & Cifelli 57 ABSTRACT I The vibrational characteristics of a percussion tool bit are varied by affixing a restraining collar thereto in accordance with the level of dampening desired. This collar is permanently affixed to the tool bit by incorporating a rigid interlock therebetween and a special compressible material is utilized therein to withstand high operating temperatures. Where the tool bit includes a detachable work tip, the tip is configured to serve as a protective shield for the collar upon penetration into materials. As part of this configuration, a conical surface is provided to facilitate withdrawal of the tool bit from penetrated materials and to avoid inadvertent removal of the tip during penetration.

10 Claims, 4 Drawing Figures 1 TOOL BIT FOR VIBRATION ATTENUATION BACKGROUND OF THE INVENTION The present invention relates to the dampening of vibrations in percussion tool bits and especially to such dampening where the tool bits are utilized to penetrate into materials. Hitherto, many different approaches have been taken to attenuate the frequency response of tool bits in achieving either increased fatigue life or re- Most dampening collars have a greater outer diame- 2O ter than the tool bit and where penetration operations are performed, they limit the depth of penetration attainable. Such collars are also subjected to much physical abuse when operating at the penetration limit. To minimize the penetration limit encounter, some collars are disposed immediately adjacent that portion of the tool bit which secures into the driving unit. However, a tool bit with such a collar is not interchangeably compatible for use with the holding provisions of all driving units. In this regard, the holding provisions most utilized to attain such compatibility is the conventional arrangement wherein a latch on the driving unit interlocks with an annular flange on the tool bit. However, this interlock is only effective over a small portion of the annular flange due to the presence of the collar in the arrangement and, therefore, undistributed wear and. more limited tool life are encountered.

Some dampening collars are merely bonded to the tool bit and separate therefrom when the bond breaks under extremely abusive environments. This problem is further aggravated at the elevated temperatures encountered under some operating conditions or when the work tip of a single piece tool bit is reshaped. Furthermore, many dampening collars include compressible materials which encounter deleterious effects to their elastic properties at elevated temperatures.

SUMMARY OF THE INVENTION to provide a tool bit having a dampening collar which is shielded from damage during penetration of materials and which does not limit the depth of penetration attainable by the tool bit.

It is another object of the present invention to provide a tool bit having a dampening collar and a detachable work tip compatibly configured to facilitate withdrawal of the tool bit from penetrated materials and to avoid inadvertent removal of the work tip during penetration.

It is a further object of the present invention to provide a tool bit having a dampening collar which includes compressible materials of high temperature endurance.

These objects are accomplished according to the present invention by structuring the dampening collar from a compressible sleeve disposed around a portion of the tool bit and compressively encasing the compressible sleeve in a rigid sleeve which engages into an annular groove on the tool bit. The compressible sleeve is fabricated of silicon based compounds to enhance the life expectancy of the collar where elevated temperatures are anticipated. When incorporated on a penetrating two-piece tool bit having a shank and a detachable work tip, the collar is shielded by the work tip. This shield is attained by configuring the work tip with a boring diameter of greater magnitude than the rigid sleeve and, therefore, the tool bit generates a clearance chamber for the collar upon penetration into materials. Hang up of the tool bit in penetrated materials is prevented by disposing a conical surface on the detachable work tip between its boring diameter and the collar.

BRIEF DESCRIPTION OF THE DRAWING The manner in which these and other objects of the invention are achieved will be best understood by reference to the following description, the appended claims, and the Figures of the attached drawing wherein:

FIG. 1 is a perspective view of a single piece tool bit to which the dampening collar of this invention is affixed;

FIG. 2 is a partial sectional view thereof, taken sub- I stantially along line 2-2 of FIG. 1 to illustrate the compressible and rigid sleeves of the dampening collar along with the groove by which the dampening collar is interlocked to the tool bit;

FIG. 3 is a perspective view of a two-piece tool bit to which the dampening collar of this invention is affixed; and

FIG. 4 is a partial sectional view thereof, taken substantially along line 44 of FIG. 3 to illustrate the compressible and rigid sleeves of the dampening collar, the groove by which the dampening collar is interlocked to the shank and the configuration of the work tip.

DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to the drawing and, more particularly, to FIG. 1, there is illustrated a single piece percussion tool bit 10 to which a dampening collar 12 in accordance with this invention is affixed. One end of the tool bit 10 includes a hexagonal portion 14 for insertion into the tool holding provisions of a driving unit (not shown). These holding provisions generally include a latch or a spring for interlocking to an annular flange 16 on the tool bit 10. A work tip 18 is disposed at the I other end of the tool bit 10 and is configured in accor The construction'of the dampening collar 12 is illustrated in FIG. 2 where a compressible sleeve 22 is intimately disposed about a portion of the shaft 20 and a rigid sleeve 24 is disposed to compressibly encase the compressible sleeve 22. An annular groove 26 is disposed around the shaft' 20 and one end of the rigid sleeve 24 is configured to engage therein. Any material having suitable elastic properties may be used in fabrieating the compressible sleeve 22, however, ferrous oxide silicon based materials have been found to belowering the flexural response of the tool bit 10. By restraining flexural freedom around a segment of the tool bit 10, the dampening collar 12 serves to lower the flexural response thereof. This is so because the compressible sleeve 22 is forced to bear against the tool bit by the rigid sleeve 24 and, therefore, must vibrate at the same frequency as the tool bit 10 or dampening will occur. Since the compressible sleeve 22 has a very low flexural response, it will not follow any high frequency vibrations propagated through the tool bit 10, so that such vibrations are dampened thereby. Therefore, the dampening collar 12 has the effect of lowering the flex- .ural response of the'tool bit 10.

The dampening effect achieved by the dampening collar 12 depends on'numerous factors and many combinations of these factors can be utilized to accomplish the particular dampening effect desired. Therefore, it would only confuse the matter to discuss any particular combination. Once a combination is determined however, the dampening collar 12 is of maximum effectiveness only so long as it remains affixed to the tool bit 10 at a precise location and the elastic properties of the compressible sleeve 22 do not deteriorate. Permanent affixment of the dampening collar 12 on the tool bit 10 is assured by the engagement of the rigid sleeve 24 into the annular groove 26 which creates an interlock therebetween. The primary cause of elastic deteriorationin the dampening collar 12 is elevated temperatures and, therefore, ferrous oxide silicon based materials which present stable elastic properties at very high temperatures are used for the compressible sleeve 22.

As illustrated in FIG. 3, the dampening collar 12 of this invention can be applied to a two piece percussion tool bit 30 having a shank 32 and a detachable work tip 34. At one end, the shank 32 includes both a hexagonal portion 36 for insertion into the tool holding provisions of the driving unit (not shown) and an annular flange 38 for interlocking therewith. The other end of the shank 32 is specially contoured to retain the detachable work tip 34 through an interference fit therewith.

Again, the exterior of the detachable work tip 34 is configured to perform a penetration operation, however, it could be configured to perform many other operations, such as tamping or riveting.

Construction of the dampening Collar 12 on the twopiece tool bit 30 is essentially identical to that described previously for the single piece tool bit 10. This construction is illustrated in FIG. 4 where the identical reference numerals are used to designate the dampening collar 12 and its parts as were used in FIG. 2. The compressible sleeve 22 is intimately disposed about a portion of the shank 32 with the rigid sleeve 24 disposed to compressibly encase the compressible sleeve 22. An annular groove 40 is disposed around the shank 32 and one end of the rigid sleeve 24 is configured to engage therein. The detachable work tip 34 of the tool bit 30 is configured to have a boring diameter X of greater magnitude than the outer diameter of the rigid sleeve 24. A conical surface 42 is disposed on the work tip 34 between the boring diameter X and the dampening collar 12, with the taper of the conical surface 42 decreasing in the direction of the dampening collar 12.

In use, the dampening collar 12 on the shank 32 lowers the flexural response of the two-piece tool bit 30 and maintains its maximum effectiveness in the exact same manner as was discussed previously for the single piece tool bit 10. However, the boring diameter X of the detachable work tip 34 creates a clearance channel for the rigid sleeve 24 as the tool bit 30 penetrates into a material. Because of this clearance channel, the dampening collar 12 can follow the work tip 34 into penetrated materials without limiting the depth of penetration. Also, the dampening collar 12 is shielded from physical abuse due to theclearance provided. The conical surface 42 serves to reduce the stepped overhang of the detachable work tip 34 relative to the dampening collar 12 and, therefore, is effective in minimizing hang up between the work tip 34 and penetrated materials. As hang up is minimized, withdrawal of the tool bit 30 after penetration is facilitated and inadvertent removal of the detachable work tip 34 during penetration is avoided.

Although it is preferable to dispose the dampening collar 12 immediately adjacent the work tip 34, as shown in FIG. 4, the clearance channel and reduction in the stepped overhang will still be accomplished to some degree where these parts are separated by a significant distance. When the dampening collar 12 is disposed immediately adjacent the work tip 34, however, the conical surface 42 may be tapered to a minimum periphery of no greater diameter thanthe outer diameter of the rigid sleeve 24 to eliminate the stepped overhang.

It should be readily appreciated by those skilled in this art that the dampening collar embodied by this invention may be applied to any percussion tool bit for lowering the flexural response thereof with maximum effectiveness. Also, where detachable work tips are utilized, a special configuration can be applied thereto for shielding the dampening collar from damage during penetration operations and eliminating the penetration limitation otherwise encountered. Furthermore, a conical surface can be included on the detachable work tip to avoid its inadvertent removal during penetration and to facilitate its withdrawal after penetration.

What I claim is:

1. A percussion tool bit for attenuating operational vibrations, comprising:

a shank through which forces are translated, said shank having a groove disposed therein;

a compressible sleeve disposed about a portion 0 said shank and in intimate contact therewith;

a rigid sleeve disposed to compressibly encase said compressible sleeve, said rigid sleeve being configured for engagement into said groove on said shank to interlock therewith; and

a work tip detachably affixed to one end of said shank.

2. The tool bit of claim 1 wherein said compressible sleeve is fabricated of a ferrous oxide silicon base material.

3. The tool bit of claim 1 wherein said work tip is configured to perform penetrating operations and includes a boring diameter of greater magnitude than the outer diameter of said rigid sleeve, said boring diameter being effective to create a clearance channel for said rigid sleeve during penetration.

4. The tool bit of claim 1 wherein said work tip is configured to perform penetrating operations and includes a conical surface, said conical surface being oriented to present a decreasing taper in the direction of said rigid sleeve to reduce hang up of said work tip in penetrated materials.

5. The tool bit of claim 1 wherein said work tip is configured to perform penetrating operations and includes a conical surface and a boring diameter, said boring diameter being of greater magnitude than the outer diameter of said rigid sleeve to create a clearance channel for said rigid sleeve during penetration, said conical surface being oriented to present a decreasing taper from said boring diameter in the direction of said rigid sleeve to reduce hang up of said work tip in pene- LII trated materials.

6. The tool bit of claim 5 wherein said compressible sleeve is fabricated of a ferrous oxide silicon base material.

7. The tool bit of claim 5 wherein said rigid sleeve is disposed immediately adjacent said work tip on said shank and said conical surface tapers to a minimum periphery of no greater diameter than the outer diameter of said rigid sleeve.

8. A vibration dampening collar for a percussion tool bit, comprising:

a compressible sleeve configured to fit about a portion of the tool bit in intimate contact therewith; and

a rigid sleeve disposed to encase said compressible sleeve, said rigid sleeve being configured to compress said compressible sleeve on the tool bit and having an interlocking portion thereon for engagement into a groove on the tool bit.

9. The vibration dampening collar of claim 8 wherein said compressible sleeve is fabricated of a ferrous oxide silicon base material.

10. A percussion tool bit for attenuating operational vibrations, comprising:

a shank through which forces are translated;

a compressible sleeve disposed about a portion of said shank and in intimate contact therewith;

a rigid sleeve disposed to compressibly encase said compressible sleeve; and

a work tip detachably affixed to one end of said shank, said work tip being configured to perform penetrating operations and including a boring diameter of greater magnitude than the outer diameter of said rigid sleeve, said boring diameter being effective to create a clearance channel for said rigid sleeve during penetration. 

1. A percussion tool bit for attenuating operational vibrations, comprising: a shank through which forces are translated, said shank having a groove disposed therein; a compressible sleeve disposed about a portion of said shank and in intimate contact therewith; a rigid sleeve disposed to compressibly encase said compressible sleeve, said rigid sleeve being configured for engagement into said groove on said shank to interlock therewith; and a work tip detachably affixed to one end of said shank.
 2. The tool bit of claim 1 wherein said compressible sleeve is fabricated of a ferrous oxide silicon base material.
 3. The tool bit of claim 1 wherein said work tip is configured to perform penetrating operations and includes a boring diameter of greater magnitude than the outer diameter of said rigid sleeve, said boring diameter being effective to create a clearance channel for said rigid sleeve during penetration.
 4. The tool bit of claim 1 wherein said work tip is configured to perform penetrating operations and includes a conical surface, said conical surface being oriented to present a decreasing taper in the direction of said rigid sleeve to reduce hang up of said work tip in penetrated materials.
 5. The tool bit of claim 1 wherein sAid work tip is configured to perform penetrating operations and includes a conical surface and a boring diameter, said boring diameter being of greater magnitude than the outer diameter of said rigid sleeve to create a clearance channel for said rigid sleeve during penetration, said conical surface being oriented to present a decreasing taper from said boring diameter in the direction of said rigid sleeve to reduce hang up of said work tip in penetrated materials.
 6. The tool bit of claim 5 wherein said compressible sleeve is fabricated of a ferrous oxide silicon base material.
 7. The tool bit of claim 5 wherein said rigid sleeve is disposed immediately adjacent said work tip on said shank and said conical surface tapers to a minimum periphery of no greater diameter than the outer diameter of said rigid sleeve.
 8. A vibration dampening collar for a percussion tool bit, comprising: a compressible sleeve configured to fit about a portion of the tool bit in intimate contact therewith; and a rigid sleeve disposed to encase said compressible sleeve, said rigid sleeve being configured to compress said compressible sleeve on the tool bit and having an interlocking portion thereon for engagement into a groove on the tool bit.
 9. The vibration dampening collar of claim 8 wherein said compressible sleeve is fabricated of a ferrous oxide silicon base material.
 10. A percussion tool bit for attenuating operational vibrations, comprising: a shank through which forces are translated; a compressible sleeve disposed about a portion of said shank and in intimate contact therewith; a rigid sleeve disposed to compressibly encase said compressible sleeve; and a work tip detachably affixed to one end of said shank, said work tip being configured to perform penetrating operations and including a boring diameter of greater magnitude than the outer diameter of said rigid sleeve, said boring diameter being effective to create a clearance channel for said rigid sleeve during penetration. 